implement web handler for QR code generation

2020-06-20 09:39:06 +02:00
parent 8410782ab8
commit 8bf9d10964
5 changed files with 333 additions and 163 deletions
--- a/cmd/qrbill-example/example.go
+++ b/cmd/qrbill-example/example.go
@@ -1,14 +1,178 @@
 package main

 import (
+	"bytes"
+	"flag"
+	"fmt"
+	"image/png"
+	"io"
 	"log"
+	"net/http"
+	"regexp"
+	"strings"

+	"github.com/davecgh/go-spew/spew"
 	"github.com/stapelberg/qrbill"
+
+	_ "net/http/pprof"
 )

+func ifEmpty(s, alternative string) string {
+	if s == "" {
+		return alternative
+	}
+	return s
+}
+
+func qrchFromRequest(r *http.Request) *qrbill.QRCH {
+	return &qrbill.QRCH{
+		CdtrInf: qrbill.QRCHCdtrInf{
+			IBAN: ifEmpty(r.FormValue("criban"), "CH0209000000870913543"),
+			Cdtr: qrbill.Address{
+				AdrTp:            qrbill.AddressTypeStructured,
+				Name:             ifEmpty(r.FormValue("crname"), "Legalize it!"),
+				StrtNmOrAdrLine1: ifEmpty(r.FormValue("craddr1"), "Quellenstrasse 25"),
+				BldgNbOrAdrLine2: ifEmpty(r.FormValue("craddr2"), ""),
+				PstCd:            ifEmpty(r.FormValue("crpost"), "8005"),
+				TwnNm:            ifEmpty(r.FormValue("crcity"), "Zürich"),
+				Ctry:             ifEmpty(r.FormValue("crcountry"), "CH"),
+			},
+		},
+		CcyAmt: qrbill.QRCHCcyAmt{
+			Amt: "",
+			Ccy: "CHF",
+		},
+		UltmtDbtr: qrbill.Address{
+			AdrTp:            qrbill.AddressTypeStructured,
+			Name:             ifEmpty(r.FormValue("udname"), "Michael Stapelberg"),
+			StrtNmOrAdrLine1: ifEmpty(r.FormValue("udaddr1"), "Brahmsstrasse 21"),
+			BldgNbOrAdrLine2: ifEmpty(r.FormValue("udaddr2"), ""),
+			PstCd:            ifEmpty(r.FormValue("udpost"), "8003"),
+			TwnNm:            ifEmpty(r.FormValue("udcity"), "Zürich"),
+			Ctry:             ifEmpty(r.FormValue("udcountry"), "CH"),
+		},
+		RmtInf: qrbill.QRCHRmtInf{
+			Tp:  "NON", // Reference type
+			Ref: "",    // Reference
+			AddInf: qrbill.QRCHRmtInfAddInf{
+				Ustrd: ifEmpty(r.FormValue("message"), "Spende 6141"),
+			},
+		},
+	}
+}
+
+var fieldNameRe = regexp.MustCompile(`<br>(&nbsp;)*([^:]+):`)
+var stringLiteralRe = regexp.MustCompile(`"([^"]*)"`)
+
+func qrHandler(format string) http.Handler {
+	if format != "png" &&
+		format != "svg" &&
+		format != "txt" &&
+		format != "html" {
+		log.Fatalf("BUG: format must be either png, svg, txt or html")
+	}
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		prefix := "[" + r.RemoteAddr + "]"
+		log.Printf("%s handling request for %s", prefix, r.URL.Path)
+		defer log.Printf("%s done: %s", prefix, r.URL.Path)
+
+		qrch := qrchFromRequest(r)
+
+		bill, err := qrch.Encode()
+		if err != nil {
+			log.Print(err)
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		var b []byte
+		switch format {
+		case "png":
+			code, err := bill.EncodeToImage()
+			if err != nil {
+				log.Print(err)
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			var buf bytes.Buffer
+			if err := png.Encode(&buf, code); err != nil {
+				log.Print(err)
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			b = buf.Bytes()
+			w.Header().Add("Content-Type", "image/png")
+
+		case "svg":
+			var err error
+			b, err = bill.EncodeToSVG()
+			if err != nil {
+				log.Print(err)
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			w.Header().Add("Content-Type", "image/svg+xml")
+
+		case "txt":
+			w.Header().Add("Content-Type", "text/plain; charset=utf-8")
+			spew.Fdump(w, qrch.Fill())
+
+		case "html":
+			w.Header().Add("Content-Type", "text/html; charset=utf-8")
+			fmt.Fprintf(w, `<html lang="en">
+<head>
+  <title>QR Bill HTML Debug Page</title>
+  <style type="text/css">
+.fieldname { font-weight: bold; }
+.stringliteral { color: blue; }
+  </style>
+</head>
+<body style="font-family: monospace">
+`)
+			sp := spew.Sdump(qrch.Fill())
+			sp = strings.ReplaceAll(sp, "\n", "<br>")
+			sp = strings.ReplaceAll(sp, " ", "&nbsp;")
+			sp = stringLiteralRe.ReplaceAllStringFunc(sp, func(stringLiteral string) string {
+				return `<span class="stringliteral">` + stringLiteral + "</span>"
+			})
+			sp = fieldNameRe.ReplaceAllStringFunc(sp, func(fieldName string) string {
+				return `<span class="fieldname">` + fieldName + "</span>"
+			})
+			fmt.Fprintf(w, "%s", sp)
+		}
+
+		// TODO: add cache control headers
+		if _, err := io.Copy(w, bytes.NewReader(b)); err != nil {
+			log.Print(err)
+			return
+		}
+	})
+}
+
 func logic() error {
-	return qrbill.Generate()
-	//return nil
+	var listen = flag.String("listen", "localhost:9933", "[host]:port to listen on")
+	flag.Parse()
+	http.Handle("/qr.png", qrHandler("png"))
+	http.Handle("/qr.svg", qrHandler("svg"))
+	http.Handle("/qr.txt", qrHandler("txt"))
+	http.Handle("/qr.html", qrHandler("html"))
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/" {
+			http.Error(w, "not found", http.StatusNotFound)
+			return
+		}
+		w.Header().Add("Content-Type", "text/html; charset=utf-8")
+		// TODO: add explanation for how to construt a URL
+		// e.g. for usage in filemaker web view
+		fmt.Fprintf(w, "<ul>")
+		fmt.Fprintf(w, `<li>PNG referenz: <a href="/qr.png">qr.png</a>`+"\n")
+		fmt.Fprintf(w, `<li>SVG scalable: <a href="/qr.svg">qr.svg</a>`+"\n")
+		fmt.Fprintf(w, `<li>debug: <a href="/qr.txt">qr.txt</a>`+"\n")
+	})
+	log.Printf("listening on http://%s", *listen)
+	return http.ListenAndServe(*listen, nil)
 }

 func main() {
--- a/go.mod
+++ b/go.mod
@@ -6,5 +6,6 @@ require (
 	github.com/aaronarduino/goqrsvg v0.0.0-20170617203649-603647895681
 	github.com/ajstarks/svgo v0.0.0-20200320125537-f189e35d30ca
 	github.com/boombuler/barcode v1.0.0
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
 )
--- a/go.sum
+++ b/go.sum
@@ -4,5 +4,7 @@ github.com/ajstarks/svgo v0.0.0-20200320125537-f189e35d30ca h1:kWzLcty5V2rzOqJM7
 github.com/ajstarks/svgo v0.0.0-20200320125537-f189e35d30ca/go.mod h1:K08gAheRH3/J6wwsYMMT4xOr94bZjxIelGM0+d/wbFw=
 github.com/boombuler/barcode v1.0.0 h1:s1TvRnXwL2xJRaccrdcBQMZxq6X7DvsMogtmJeHDdrc=
 github.com/boombuler/barcode v1.0.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e h1:MRM5ITcdelLK2j1vwZ3Je0FKVCfqOLp5zO6trqMLYs0=
 github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e/go.mod h1:XV66xRDqSt+GTGFMVlhk3ULuV0y9ZmzeVGR4mloJI3M=
--- a/qrbill.go
+++ b/qrbill.go
@@ -9,14 +9,12 @@
 package qrbill

 import (
+	"bytes"
 	"image"
-	"log"
-	"os"
 	"strings"

 	"github.com/aaronarduino/goqrsvg"
 	svg "github.com/ajstarks/svgo"
-	"github.com/boombuler/barcode"
 	"github.com/boombuler/barcode/qr"

 	// We currently read the swiss cross PNG version.
@@ -34,17 +32,16 @@ import (
 // https://github.com/codebude/QRCoder/wiki/Advanced-usage---Payload-generators#317-swissqrcode-iso-20022

 const (
-	// QRType is an unambiguous indicator for the Swiss QR Code. Fixed value
-	// "SPC".
+	// QRType is an unambiguous indicator for the Swiss QR Code. Fixed value.
 	QRType = "SPC" // Swiss Payments Code

 	// Version contains the version of the specifications (Implementation
 	// Guidelines) in use on the date on which the Swiss QR Code was
 	// created. The first two positions indicate the main version, the following
-	// two positions the sub-version. Fixed value of "0200" for Version 2.0.
+	// two positions the sub-version. Fixed value.
 	Version = "0200" // Version 2.0

-	// CodingType is the character set code. Fixed value "1".
+	// CodingType is the character set code. Fixed value.
 	CodingType = "1" // UTF-8 restricted to the Latin character set
 )

@@ -58,7 +55,6 @@ const (

 // - fixed length: 21 alphanumeric characters
 // - only IBANs with CH or LI country code permitted
-var iban = "CH0209000000870913543"

 type Address struct {
 	AdrTp            AddressType
@@ -106,176 +102,93 @@ type QRCH struct {
 	RmtInf    QRCHRmtInf  // Payment reference
 }

-func (q *QRCH) QRContents() string {
-	return strings.Join([]string{
-		q.Header.QRType,
-		q.Header.Version,
-		q.Header.Coding,
-
-		q.CdtrInf.IBAN,
-
-		string(q.CdtrInf.Cdtr.AdrTp),
-		q.CdtrInf.Cdtr.Name,
-		q.CdtrInf.Cdtr.StrtNmOrAdrLine1,
-		q.CdtrInf.Cdtr.BldgNbOrAdrLine2,
-		q.CdtrInf.Cdtr.PstCd,
-		q.CdtrInf.Cdtr.TwnNm,
-		q.CdtrInf.Cdtr.Ctry,
-
-		string(q.UltmtCdtr.AdrTp),
-		q.UltmtCdtr.Name,
-		q.UltmtCdtr.StrtNmOrAdrLine1,
-		q.UltmtCdtr.BldgNbOrAdrLine2,
-		q.UltmtCdtr.PstCd,
-		q.UltmtCdtr.TwnNm,
-		q.UltmtCdtr.Ctry,
-
-		q.CcyAmt.Amt,
-		q.CcyAmt.Ccy,
-
-		string(q.UltmtDbtr.AdrTp),
-		q.UltmtDbtr.Name,
-		q.UltmtDbtr.StrtNmOrAdrLine1,
-		q.UltmtDbtr.BldgNbOrAdrLine2,
-		q.UltmtDbtr.PstCd,
-		q.UltmtDbtr.TwnNm,
-		q.UltmtDbtr.Ctry,
-
-		q.RmtInf.Tp,
-		q.RmtInf.Ref,
-		q.RmtInf.AddInf.Ustrd,
-		q.RmtInf.AddInf.Trailer,
-	}, "\n")
+func (q *QRCH) Fill() *QRCH {
+	clone := &QRCH{}
+	*clone = *q
+	clone.Header.QRType = QRType
+	clone.Header.Version = Version
+	clone.Header.Coding = CodingType
+	clone.RmtInf.AddInf.Trailer = "EPD" // TODO: constant
+	return clone
 }

-// https://www.paymentstandards.ch/dam/downloads/qrcodegenerator.java
-func generateSwissQrCode(content string) error {
-	// generate the qr code from the payload
-	code, err := qr.Encode(content, qr.M, qr.Auto)
-	if err != nil {
-		return err
-	}
+func (q *QRCH) Encode() (*Bill, error) {
+	f := q.Fill()
+	//f := q.Fill()
+	// TODO: data content must be no more than 997 characters
+	// TODO: truncate fields where necessary
+	return &Bill{
+		qrcontents: strings.Join([]string{
+			f.Header.QRType,
+			f.Header.Version,
+			f.Header.Coding,

-	// overlay the qr code with a Swiss Cross
-	combined, err := overlayWithSwissCross(code)
-	if err != nil {
-		return err
-	}
-	_ = combined
+			f.CdtrInf.IBAN,

-	return nil
+			string(f.CdtrInf.Cdtr.AdrTp),
+			f.CdtrInf.Cdtr.Name,
+			f.CdtrInf.Cdtr.StrtNmOrAdrLine1,
+			f.CdtrInf.Cdtr.BldgNbOrAdrLine2,
+			f.CdtrInf.Cdtr.PstCd,
+			f.CdtrInf.Cdtr.TwnNm,
+			f.CdtrInf.Cdtr.Ctry,
+
+			string(f.UltmtCdtr.AdrTp),
+			f.UltmtCdtr.Name,
+			f.UltmtCdtr.StrtNmOrAdrLine1,
+			f.UltmtCdtr.BldgNbOrAdrLine2,
+			f.UltmtCdtr.PstCd,
+			f.UltmtCdtr.TwnNm,
+			f.UltmtCdtr.Ctry,
+
+			f.CcyAmt.Amt,
+			f.CcyAmt.Ccy,
+
+			string(f.UltmtDbtr.AdrTp),
+			f.UltmtDbtr.Name,
+			f.UltmtDbtr.StrtNmOrAdrLine1,
+			f.UltmtDbtr.BldgNbOrAdrLine2,
+			f.UltmtDbtr.PstCd,
+			f.UltmtDbtr.TwnNm,
+			f.UltmtDbtr.Ctry,
+
+			f.RmtInf.Tp,
+			f.RmtInf.Ref,
+			f.RmtInf.AddInf.Ustrd,
+			"EPD", // TODO: constant
+		}, "\n"),
+	}, nil
 }

-func overlayWithSwissCross(code barcode.Barcode) (image.Image, error) {
-	// TODO: bundle a swiss cross image
-	const swissCrossPath = "/home/michael/go/src/github.com/stapelberg/qrbill/third_party/swiss-cross/CH-Kreuz_7mm/CH-Kreuz_7mm.png"
-
-	// TODO: read swiss cross image
-	f, err := os.Open(swissCrossPath)
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
-	m, _, err := image.Decode(f)
-	if err != nil {
-		return nil, err
-	}
-	log.Printf("bounds: %+v", m.Bounds())
-	return nil, nil
+type Bill struct {
+	qrcontents string
 }

-func Generate() error {
-	log.Printf("hey!")
-
-	content := (&QRCH{
-		Header: QRCHHeader{
-			QRType:  QRType,
-			Version: Version,
-			Coding:  CodingType,
-		},
-		CdtrInf: QRCHCdtrInf{
-			IBAN: iban,
-			Cdtr: Address{
-				AdrTp:            AddressTypeStructured, // CR AddressTyp
-				Name:             "Legalize it!",        // CR Name
-				StrtNmOrAdrLine1: "Quellenstrasse 25",   // CR Street or address line 1
-				BldgNbOrAdrLine2: "",                    // CR Building number or address line 2
-				PstCd:            "8005",                // CR Postal code
-				TwnNm:            "Zürich",              // CR City
-				Ctry:             "CH",                  // CR Country
-			},
-		},
-		CcyAmt: QRCHCcyAmt{
-			Amt: "",
-			Ccy: "CHF",
-		},
-		UltmtDbtr: Address{
-			"S",                  // UD AddressTyp
-			"Michael Stapelberg", // UD Name
-			"Brahmsstrasse 21",   // UD Street or address line 1
-			"",                   // UD Building number or address line 2
-			"8003",               // Postal code
-			"Zürich",             // City
-			"CH",                 // Country
-		},
-		RmtInf: QRCHRmtInf{
-			Tp:  "NON", // Reference type
-			Ref: "",    // Reference
-			AddInf: QRCHRmtInfAddInf{
-				Ustrd:   "Spende 6141",
-				Trailer: "EPD",
-			},
-		},
-	}).QRContents()
-
+func (b *Bill) EncodeToSVG() ([]byte, error) {
 	// as per https://www.paymentstandards.ch/dam/downloads/ig-qr-bill-en.pdf, section 5.1:
 	// Error correction level M (redundancy of around 15%)

-	// TODO: data content must be no more than 997 characters
+	// Section 4.2.1: Character set:
+	// UTF-8 should be used for encoding

-	// https://www.PaymentStandards.CH/FAQ)
-	// TODO: auf version 24 (46mm x 46mm) skalieren
-
-	// version 25 with 117 x 117 modules
-
-	// minimum module size of 0.4mm (recommended for printing)
-
-	// TODO: overlay the swiss cross logo!
-	// TODO: verify dimensions when printed
-
-	// TODO: ensure UTF-8
-	code, err := qr.Encode(content, qr.M, qr.Auto)
+	code, err := qr.Encode(b.qrcontents, qr.M, qr.Unicode)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	f, err := os.Create("/tmp/code.svg")
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-	s := svg.New(f)
+	var buf bytes.Buffer
+	s := svg.New(&buf)
 	qrsvg := goqrsvg.NewQrSVG(code, 5)
 	qrsvg.StartQrSVG(s)
 	if err := qrsvg.WriteQrSVG(s); err != nil {
-		return err
+		return nil, err
 	}
+
+	// TODO: overlay the swiss cross logo!
+
 	s.End()
-	if err := f.Close(); err != nil {
-		return err
-	}
-
-	if err := generateSwissQrCode(content); err != nil {
-		return err
-	}
-
-	/*
-		code, err := qrcode.NewWithForcedVersion(content, 25, qrcode.Medium)
-		if err != nil {
-			return err
-		}
-		log.Printf("code: %v", code)
-		const pixelsPerMillimeter = 10
-		return code.WriteFile(-2, "/tmp/code.png")
-	*/
-	return nil
+	return buf.Bytes(), nil
+}
+
+func (b *Bill) EncodeToImage() (image.Image, error) {
+	return generateSwissQrCode(b.qrcontents)
 }
--- a/qrcodegenerator.go
+++ b/qrcodegenerator.go
@@ -0,0 +1,90 @@
+package qrbill
+
+import (
+	"image"
+	"image/draw"
+	"os"
+
+	"github.com/boombuler/barcode"
+	"github.com/boombuler/barcode/qr"
+)
+
+// This is a port of the Java 1.7 reference example from paymentstandards.ch:
+// https://www.paymentstandards.ch/dam/downloads/qrcodegenerator.java
+//
+// The priority was to write idiomatic Go code first, and match the reference
+// example as good as possible second.
+
+const (
+	swissCrossEdgeSidePx = 166
+
+	swissCrossEdgeSideMm = 7
+
+	// The edge length of the qrcode inclusive its white border.
+	qrCodeEdgeSideMm = 42 + 13
+
+	qrCodeEdgeSidePx = swissCrossEdgeSidePx / swissCrossEdgeSideMm * qrCodeEdgeSideMm
+)
+
+func generateSwissQrCode(payload string) (image.Image, error) {
+	// generate the qr code from the payload
+	qrCodeImage, err := generateQrCodeImage(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	// overlay the qr code with a Swiss Cross
+	return overlayWithSwissCross(qrCodeImage)
+}
+
+func generateQrCodeImage(payload string) (image.Image, error) {
+	code, err := qr.Encode(payload, qr.M, qr.Unicode)
+	if err != nil {
+		return nil, err
+	}
+	qrcode, err := barcode.Scale(code, qrCodeEdgeSidePx, qrCodeEdgeSidePx)
+	if err != nil {
+		return nil, err
+	}
+	return qrcode, nil
+}
+
+func overlayWithSwissCross(qrCodeImage image.Image) (image.Image, error) {
+	// TODO: bundle the swiss cross image instead of reading it
+	const swissCrossPath = "/home/michael/go/src/github.com/stapelberg/qrbill/third_party/swiss-cross/CH-Kreuz_7mm/CH-Kreuz_7mm.png"
+
+	f, err := os.Open(swissCrossPath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	swissCrossImage, _, err := image.Decode(f)
+	if err != nil {
+		return nil, err
+	}
+
+	combinedQrCodeImage := image.NewRGBA(qrCodeImage.Bounds())
+
+	{
+		sr := qrCodeImage.Bounds() // source rect
+		destRect := image.Rectangle{image.Point{0, 0}, sr.Size()}
+		draw.Draw(combinedQrCodeImage, destRect, qrCodeImage, sr.Min, draw.Src)
+	}
+
+	{
+		sr := swissCrossImage.Bounds() // source rect
+		const swissCrossPosition = (qrCodeEdgeSidePx / 2) - (swissCrossEdgeSidePx / 2)
+		destPoint := image.Point{
+			X: swissCrossPosition,
+			Y: swissCrossPosition,
+		}
+		// Convert the source image bounds into the destination image’s coordinate
+		// space:
+		destRect := image.Rectangle{
+			destPoint,
+			destPoint.Add(sr.Size()),
+		}
+		draw.Draw(combinedQrCodeImage, destRect, swissCrossImage, sr.Min, draw.Src)
+	}
+	return combinedQrCodeImage, nil
+}